At long last, the energy economy is central to local, state, national and global political and social agendas. This is welcome news: It opens to door to addressing meaningfully the linked issues of energy security, global warming and the opportunity to redirect the $700 billion we spend each year on imported fuels instead into building innovative companies and moving into sustainable job growth.

Thankfully, both presidential candidates, Sens. Barack Obama and John McCain, are talking substantively about energy.

Both candidates are cognizant of the true risks that global warming presents, and as a result support a cap-and-trade system to put a price on pollution and environmental damage.

Both candidates also support an expanded emphasis on research, and both recognize the need to re-engage the United States as a leader in this area - something that, sadly, President Bush neglected to our environmental and economic peril.

The similarity between the candidates, however, ends there - at the proverbial 30,000-foot level. With the long lack of leadership in this area, the details not only matter, they are the real story.

First and foremost, 50 years of economic and technology policy clearly point to a simple, yet often illusive, guiding principle: We need a strategy that balances support for basic and applied research (the "technology push"), and at the same time a plan for market development ("demand pull"). Sounds simple, yet it is rarely done in practice because it takes vision and coordination across agencies.

To usher in a clean energy economy, the Obama plan calls for a 10-year, $150 billion program that balances support for an expanded R&D portfolio - which everyone agrees is vitally needed - with support for market development and expansion.

Obama also calls for a renewable energy portfolio standard of 10 percent of electricity nationwide to come from renewable energy by 2012 and 25 percent by 2025. McCain simply has no comparable articulated vision for a balanced approach, and in the past has routinely voted against arguably the most effective clean energy policy: a production tax credit and investment tax credit package for renewable energy supplies. Thankfully these credits were part of the energy package passed by the Senate and in the recent financial bailout package. Obama has been a long-standing supporter of this incentive.

Public investments of this sort in the United States have been repaid many times over. A well-organized and successful campaign to double the federal medical/biotechnology R&D budget during the 1990s resulted in an eleven-to-twelve-fold increase in private-sector investment and innovation. The recent run-up in investment in nanotechnology is already paying off at a ratio of almost 20 to 1. Innovation, simply put, is good business and good for business.

Second, the candidates differ markedly on the mechanism and targets for a federal cap-and-trade system to first limit, and then reduce, greenhouse gas emissions. Obama has endorsed a cap-and-trade system where the permits to emit are all auctioned. McCain proposes to initially give them away. The economic consensus is overwhelming here: Without a price from Day One for permits, the government forfeits a vital revenue stream, and is tremendously counterproductive because the largest polluters get the least incentive to innovate and clean up their emissions.

Third, we must make major changes in the transportation sector to encourage innovation, set clear standards and move beyond partisan battles that lead, at best, to minimal and incremental progress. Obama has committed to rapid deployment of 1 million plug-in hybrid vehicles, a 4 percent annual increase in vehicle efficiency standards, and redirecting the U. S. Environmental Protection Agency to support states that innovate to achieve greenhouse gas reductions. This last element is of particular interest to California because the Bush administration has prevented our state from implementing regulations to reduce greenhouse gas emissions from new vehicles. On the campaign trail, McCain has equivocated on what he would do in this regard.

Clean energy is also the best diplomacy, an area where the United States must re-engage after eight years of silence. Energy infrastructure is needed around the planet, particularly in the poorest developing nations. Renewable energy and energy efficiency can often be installed and put into operation far faster than traditional fossil fuel facilities, and with far greater flexibility on home, village, town or city scales. Green-collar jobs benefit not only U.S. communities, but those in developing nations as well. The United States, with the world's most extensive - though historically not always the best-funded - international development network, could speed the clean energy revolution, putting economic opportunity and environmental quality squarely in the forefront of the priorities of every community and national leader worldwide.

With energy finally back on the priority list, it is vital to back up broad sentiments about energy independence and climate with innovative programs and partnerships. In this the candidates differ greatly.